diff options
Diffstat (limited to 'arch/um/drivers/random.c')
| -rw-r--r-- | arch/um/drivers/random.c | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/arch/um/drivers/random.c b/arch/um/drivers/random.c new file mode 100644 index 000000000..778a0e52d --- /dev/null +++ b/arch/um/drivers/random.c @@ -0,0 +1,176 @@ +/* Copyright (C) 2005 - 2008 Jeff Dike <jdike@{linux.intel,addtoit}.com> */ + +/* Much of this ripped from drivers/char/hw_random.c, see there for other + * copyright. + * + * This software may be used and distributed according to the terms + * of the GNU General Public License, incorporated herein by reference. + */ +#include <linux/sched/signal.h> +#include <linux/module.h> +#include <linux/fs.h> +#include <linux/interrupt.h> +#include <linux/miscdevice.h> +#include <linux/delay.h> +#include <linux/uaccess.h> +#include <init.h> +#include <irq_kern.h> +#include <os.h> + +/* + * core module and version information + */ +#define RNG_VERSION "1.0.0" +#define RNG_MODULE_NAME "hw_random" + +#define RNG_MISCDEV_MINOR 183 /* official */ + +/* Changed at init time, in the non-modular case, and at module load + * time, in the module case. Presumably, the module subsystem + * protects against a module being loaded twice at the same time. + */ +static int random_fd = -1; +static DECLARE_WAIT_QUEUE_HEAD(host_read_wait); + +static int rng_dev_open (struct inode *inode, struct file *filp) +{ + /* enforce read-only access to this chrdev */ + if ((filp->f_mode & FMODE_READ) == 0) + return -EINVAL; + if ((filp->f_mode & FMODE_WRITE) != 0) + return -EINVAL; + + return 0; +} + +static atomic_t host_sleep_count = ATOMIC_INIT(0); + +static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size, + loff_t *offp) +{ + u32 data; + int n, ret = 0, have_data; + + while (size) { + n = os_read_file(random_fd, &data, sizeof(data)); + if (n > 0) { + have_data = n; + while (have_data && size) { + if (put_user((u8) data, buf++)) { + ret = ret ? : -EFAULT; + break; + } + size--; + ret++; + have_data--; + data >>= 8; + } + } + else if (n == -EAGAIN) { + DECLARE_WAITQUEUE(wait, current); + + if (filp->f_flags & O_NONBLOCK) + return ret ? : -EAGAIN; + + atomic_inc(&host_sleep_count); + reactivate_fd(random_fd, RANDOM_IRQ); + add_sigio_fd(random_fd); + + add_wait_queue(&host_read_wait, &wait); + set_current_state(TASK_INTERRUPTIBLE); + + schedule(); + remove_wait_queue(&host_read_wait, &wait); + + if (atomic_dec_and_test(&host_sleep_count)) { + ignore_sigio_fd(random_fd); + deactivate_fd(random_fd, RANDOM_IRQ); + } + } + else + return n; + + if (signal_pending (current)) + return ret ? : -ERESTARTSYS; + } + return ret; +} + +static const struct file_operations rng_chrdev_ops = { + .owner = THIS_MODULE, + .open = rng_dev_open, + .read = rng_dev_read, + .llseek = noop_llseek, +}; + +/* rng_init shouldn't be called more than once at boot time */ +static struct miscdevice rng_miscdev = { + RNG_MISCDEV_MINOR, + RNG_MODULE_NAME, + &rng_chrdev_ops, +}; + +static irqreturn_t random_interrupt(int irq, void *data) +{ + wake_up(&host_read_wait); + + return IRQ_HANDLED; +} + +/* + * rng_init - initialize RNG module + */ +static int __init rng_init (void) +{ + int err; + + err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0); + if (err < 0) + goto out; + + random_fd = err; + + err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt, + 0, "random", NULL); + if (err) + goto err_out_cleanup_hw; + + sigio_broken(random_fd, 1); + + err = misc_register (&rng_miscdev); + if (err) { + printk (KERN_ERR RNG_MODULE_NAME ": misc device register " + "failed\n"); + goto err_out_cleanup_hw; + } +out: + return err; + +err_out_cleanup_hw: + os_close_file(random_fd); + random_fd = -1; + goto out; +} + +/* + * rng_cleanup - shutdown RNG module + */ + +static void cleanup(void) +{ + free_irq_by_fd(random_fd); + os_close_file(random_fd); +} + +static void __exit rng_cleanup(void) +{ + os_close_file(random_fd); + misc_deregister (&rng_miscdev); +} + +module_init (rng_init); +module_exit (rng_cleanup); +__uml_exitcall(cleanup); + +MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver"); +MODULE_LICENSE("GPL"); |